A Cross-sectional Study Of Low-carbohydrate Diets And Obesity

Objective Low-carbohydrate diets（LCDs）are often used for weight control in obese patients in Europe and America,but have been less studied and controversial in the general population.Compared to weight or body mass index（BMI）,adult weight change,which depends on accumulation of fat rather than muscle,is more likely to reflect obesity.Different food sources of LCDs（plant-based and animal-based LCDs）may have inconsistent association with obesity.Unlike Europeans and Americans,Chinese have a diet with high carbohydrate,but there are few studies on the relationship between LCDs and health in China.Therefore,it is significance to explore the association of LCDs with obesity in the background of high carbohydrate intake.We investigated the associations of overall LCD,plant-based LCD and animal-based LCD with general obesity,central obesity and weight change in Lu’an City by creating LCDs score,which provide epidemiological evidence and dietary guidance for obesity prevention and control.Methods Based on the complex sampling method,participants in our study were selected from permanent residents in two districts and two counties of Lu’an city,Anhui Province from July 2020 to September 2021.Demographic information,body weight at20 years old,dietary behavior and lifestyle of the respondents were obtained through questionnaires.The percentage of energy from three macronutrients were calculated according to the China Food Composition and divided into 11 equal parts,and the positive（the score increased from 0 to 10 with the increase of quantile）and negative（the score decreased from 10 to 0 with the increase of quantile）scores were assigned.Overall LCD score was calculated by assigning negative values to total carbohydrates and positive values to total fat and protein.For plant-based LCD,total carbohydrate was assigned negatively,while vegetative fat and protein were assigned positively.In animal-based LCD,total carbohydrate was negatively assigned,while animal fat and protein were positively assigned.In addition,Body weight and height were obtained by physical examinations.BMI was calculated according to the measured weight and height.General obesity was defined as BMI≥28kg/m~2,central obesity was defined as waist circumference≥90cm for men or≥85cm for women,and weight change is the difference between the weight measured now and the weight at age 20.Logistic regression was used to analyze the influence of LCDs on general obesity and central obesity,and multiple linear regression was used to explore the relationship between LCDs and body weight change.Results A total of 2471 individuals were included in the present analysis,including1004 males（40.6%）and 1467 females（59.4%）,with an average age of 51.5±15.8 years.There were 384 people with general obesity（15.5%）and 15.8%with standard obesity,1041 people with central obesity（42.1%）and 39.3%with standard obesity.After adjusting for confounding factors,multivariate logistic regression analysis showed that overall LCD(OR=1.53,95%CI:1.06-2.20,P _trend=0.023)and plant-based LCD(OR=1.69,95%CI:1.17-2.45,P _trend<0.001)were positively correlated with general obesity,but animal-based LCD was not associated with general obesity（P>0.05）.Besides,overall LCD,plant-based LCD,and animal-based LCD were not significantly associated with central obesity,and P values were greater than 0.05.The linear regression results of LCDs and body weight change suggest that body weight change increases linearly with the overall LCD and plant-based LCD scores.Compared with the lowest quintile,the highest quintile of overall LCD and plant-based LCD increased by 0.18kg(P _trend=0.047)and 0.17kg(P _trend=0.003)respectively.Conclusion Total LCD and plant-based LCD were found to be associated with increased risk of general obesity,and the results of body weight change were consistent with this,the higher the scores of total LCD and plant-based LCD,the greater the weight gain was compared with the weight gain of 20 years old.The results suggest that the association between adherence to LCDs diet and obesity in Lu’an population may be different from that in Europe and America.